Spyder,
If you just lengthen the tongue, the hitch weight will go down a little (unless the new tongue is made out of lead) - adding 12" to your trailer, that's now about 8.5' from hitch to axle, will reduce the hitch weight from 140lb to about 130lb.
Adding, say, 100lb (40lb spare + 30lb box + 30lb contents) to the lengthened tongue (but near the trailer body) will add about 70lb to the hitch weight, to make it about 200lb. That's a high percentage of the trailer weight, 18%, but providing your tow vehicle can handle it, that's no problem.
I believe some of those boxes can be really heavy, so youwill need to check that figure.
Lengthening the tongue
and adding weight on it will increase the bending load on it a lot - the lengthening adds about 30-50% and the extra weight adds another 40-50%. So in round numbers you need to double the strength of the tongue. This increase is most needed in the area under the front of the trailer body, because this is where the bending load is highest.
To double the strength, you don't need to double the size. You can measure your existing tongue, look up its strength on my
tongue strength page and then pick a section that's around twice as strong. Typically, if you have a tongue that's 2"x2" tube, you will nearly double its strength by going to the same tube in 2"x3". Alternatively, a simple way to improve the strength of the tongue would be to add another 2"x2" tube under the existing one - add 2-3 feet of full-height second tube and then taper the ends away over 6-12".
Is that all as clear as mud? If so, say and I'll try to do better.
Andrew
Posted: Wed Feb 08, 2006 10:43 am
